I am in the process of rewiring my 1975 Cabot 36 sailboat with plan to sail the Caribbean for a year and potentially further later. I have put together a wiring diagram (link) that lays out what I am planning to use and how it connects. This is mostly based on using Nigel Calder's Mechanical and Electrical Handbook, MaineSail's website, and several forums and other online sources.

I would really like some input into if there is anything I have shown that just looks like a bad idea or is dangerous. I am not an expert electrician by any means but as a boat owner I am learning to do a little bit of just about everything.

Please let me know if you need additional information and thank you for your input.

I like that you can run the DC panel with the house, starter, or both banks.

I don't like that you can't start the engine with only the house bank. To me, the redundancy of having two separate banks is not just for the case where one bank is run flat. It's also that batteries sometimes fail (internal shorts, whatever), so I feel you should design the system so the boat is completely operational if one bank goes offline. It's hard to tell from the size of the photos, but it looks like all of your switches are 'on-off' style, so it looks like you are always combining the battery banks whenever you turn the engine starter circuit on. You wouldn't want to combine the banks if your engine bank is completely flat and you are trying to start off of the house bank. I'd like to add that this advice is a bit against the grain -- a lot of well respected marine authorities advocate a very hands off and simple system with on-off-combine switches and battery combiners, that are not capable of using either bank for any purpose. I think their advice is fine for many people, but prefer more redundancy for myself.

Your small DC fuse block can't be run off of the starter bank. This doesn't matter if you only connect the combiner to it, but some people put things (like bilge pumps, solar controllers, and etc) on these kinds of panels (so they can switch the main panel 'off' but leave a few things on) -- in that case I'd move the feed so that these loads can be run off of either bank.

I like that you are using nice terminal blocks instead of just piling more wires onto the battery terminals. That's great. Now I am going to have weird advice-- many people only feel comfortable buyingelectricalparts that are marketed as 'marine grade', but there are better systems from the industrial automation world. The specs are better, they are approved by the ABYC (and etc), and many large custom boats use these systems. So... Consider DIN rail terminal blocks -- they come for all wire sizes, to fit everything from your combiner to large battery cables. With these you can make a much more compact bus with better wire routing, easier expandability, and no need for crimping terminals that you then bolt onto a terminal block. I feel that crimped terminals are a source of error. This style of terminal block is also more finger safe, which is especially important for your AC wiring.

Good point on fusing the starter battery bank. I have some 150 amp mrbf fuses that i should be able to reuse for this.

You are correct about the battery switches being the on-off style. The way I plan to set it up is for the "house bank" switch to be connected to the output side of the "combine" switch and then from this post it connects to the distribution panel. the "starting" switch is connected to the input side of the "combine" switch, so when the "house" bank is on but the "combine" is off the distribution panel is only powered by the "house". if the "starting" switch is on and "combine" is on but the "house" house is off then the distribution panel is powered only by the "starting" bank. (I have never tried this but in theory) If the starting bank is dead (shorted) I can turn "house" on, "combine" on and "starting" off to start the engine with the house bank only since the input side of "combine" is connected to the output side of the "starting" and the engine is connected to the output side of "starting".

Someone please provide some comments if you think that makes since and works. I have never tried starting off the house with this configuration but in my head it makes since. (i could be missing something)

You are correct that the small DC fuse block is meant for my "always on" circuits. I will be putting bilge pump, alarms, clock memory, and maybe others on this block rather then the main distribution panel. I currently plan to put it connected before the battery switch so that it is on even if the battery switch is off. How would i do this to both house and starting bank without creating a direct connection between the 2 banks?

I have not looked into any alternative terminal blocks before I will have to do some more research about the DIN options. Being somewhat new to all of this I do tend to stick with most recognizable names (Blue Seas) to avoid using something I shouldn't and causing unintended issues. But if there are better options I am happy to do some more homework if it means a better product at a lower cost.

Oh, OK, I misunderstood your diagram. I drew what I think you mean -- is the drawing right?

I think that's fine and will work well.

If you want to gold plate this, I'd add a switch for the engine. And move the fused bilge/sensor/whatever loads to the common bus, instead of connecting it directly to the house bank. But that's just to cover weird cases -- like having a working bilge pump if your house bank shorts. Or being able to work on your engine without turning off the whole boat (with the lights on). I think your Beta engine is better setup than most -- on some engine's I've had, you couldn't pull the dipstick without shorting it on the back of the alternator. Every Yanmar I've had is crazily stressful to change the impeller without shorting the screwdriver on the starter.

And the 'common bus' has it's own trade off: if you turn off both battery switches, you power cycle your battery monitor, clock, or whatever. Personally, I like being able to do that.

But, really, that's just details. You can easily accomplish the same thing (bilge pump works with a down house bank) by disconnecting the lug on the house bank and flipping the house switch on. To me, the important thing is an immediate combination of switches where you'll have a working autopilot/depthsounder/engine/gps if one bank shorts out. I think it's OK to have to break out a wrench for other cases, if you understand the system. And, to me, a good metaphor is 'common bus' and 'connect house batteries to common bus' and 'connect starter battery to common bus'.

I just think of the fools that have abandoned their boat on a crappy passage because their house bank was running flat and they didn't know how to setup the electrical system so they'd at least have a GPS. It's easy to sit on a dry couch and call them idiots, but ... there but the grace of god I go -- so I like it to not require tools or much thought to work around common situations. Which you already have for most cases.

An out of work recording engineer and I rewired my 1973 Pearson 36. We use all tinned fine strand copper wire from Pacer Marine and their waterproof connectors everywhere. Also went with Blue Sea modular circuit panels and their DC meter.

Since Skylark is mostly in northern Europe (not so sunny), I chose the SuperWind 350 for alternative power. It is the most expensive wind generator on the market, but the quality of construction and the excellent service the firm gives made me sure that I made the right choice.

One starter and 3 house batteries would be better. A charged group 27 will be easily capable of starting your engine, and the third battery will reduce charging times.

Couldn't make out the diagram, but wondered about the alternator output. Better to wire it straight to the house bank and charge the start battery with a combiner. Don't route the alternator through a switch that could be inadvertently turned off while the engine is running, especially if you have a regulator which senses voltage at the battery.

Correct Cable selection for Marine Applications
System diagrams look good what are you using for cabling between devices

The best cable application is a low smoke zero halogen finely stranded cable 110-120 deg cable massive amp carrying capacity so you are able to downsize core sizes designed for marine application to reduce toxic smoke from fires these cables are used by Nato Us Navy, Coast Guard, Australian and British Navy,Riveria Maritimo, list goes on approved by Llyods
Expense wise with down sizing and flexibility of installation (saves labour time on install about 30% quicker)taken into consideration pricing will be competitive
Triangle Cables produce these in America Australia and Tahiland
the marine Range is also complemented by a 2hr Fire Retardant Cable for intrinsic systems

Correct Cable selection for Marine Applications
System diagrams look good what are you using for cabling between devices

The best cable application is a low smoke zero halogen finely stranded cable 110-120 deg cable massive amp carrying capacity so you are able to downsize core sizes designed for marine application to reduce toxic smoke from fires these cables are used by Nato Us Navy, Coast Guard, Australian and British Navy,Riveria Maritimo, list goes on approved by Llyods
Expense wise with down sizing and flexibility of installation (saves labour time on install about 30% quicker)taken into consideration pricing will be competitive
Triangle Cables produce these in America Australia and Tahiland
the marine Range is also complemented by a 2hr Fire Retardant Cable for intrinsic systems

Just a note of caution on the terminology here, LSOH, or LSZH cable refers to the plastics in the insulation and sheathing only, it is a requirement for all confined areas, underground or similar spaces that may be subject to containment of the products of combustion and the need is defined by a mix of regulations, toxicity levels (volume of the nasties produced etc) and durability / recovery time post fire incident. "Intrinsic" refers to the area hazard, such as running cables through a coal mine, a fuel tank or in a gas locker rather than under a settee berth. 2 hr fire retardandt must be considered as an FRL against a fire curve, do we talk ISO or Hc etc. Additionally, we must look to the end condition as it also requires consideration of the supporting arrangements if we expect it to continue to operate to design current capacity and voltage. There are so many detailed variants that inexperienced folks can get mislead, spend an absolute fortune on the wrong cable for their application.
So please, do not just go and buy an expensive cable to meet terminology that is not actually relevant to the application.
Roger

I am in the process of rewiring my 1975 Cabot 36 sailboat with plan to sail the Caribbean for a year and potentially further later. I have put together a wiring diagram (link) that lays out what I am planning to use and how it connects. This is mostly based on using Nigel Calder's Mechanical and Electrical Handbook, MaineSail's website, and several forums and other online sources.

I would really like some input into if there is anything I have shown that just looks like a bad idea or is dangerous. I am not an expert electrician by any means but as a boat owner I am learning to do a little bit of just about everything.

Please let me know if you need additional information and thank you for your input.

I'm thinking you are going to spend a whole bunch of boat bucks. Looks complicated, full of failure points. Some where down the road you will wonder why you spent all the bucks on those battery's. I opt for a more simple system and conventional batts.
Not trying to discourage, go look at a few cruising boats, check out there electric systems. Keep it simple and robust!

2) Similarly, keep your wiring diagram updated so that when you are finished you have a complete an accurate diagram to go back and refer to.

3) I agree with the suggestion that you only need one starter battery, assuming you have a 12 Volt system and a 12 Volt starter. I would be interested in learning why you had planned for two starter batteries.

4) I think Blue Seas Systems components are top notch. With respect to the poster that recommended alternatives, I only used BSS goods. (No affiliation other than as a satisfied customer.)

5) Fusing the starter battery is considered optional, although I did mine. In the event of a fault, I wanted something to interrupt that current other than a fire. I sized the fuse to protect the cable, and I probably used the 75 degree tables in the NEC. I'm not at the boat now and I can't remember what size I installed.

6) No one has discussed terminating all of these cables and what type of crimper to use, but a search on this forum will uncover several threads covering that topic.

7) You mentioned you may add solar and/or wind generation at a future date. Just make sure you leave some spare lugs to connect to.

I also made a diagram of the switch specifically. This shows what I am thinking which seems a little different then the version recommended. I think it seems simple but if there is something wrong with it please let me know.https://plus.google.com/u/0/photos/p...JOOnO3ip5iguAE

I originally was thinking 2 starter batteries and 2 house batteries because that is how my boat is current set up. I was just going to reuse the existing battery boxes. The 2 banks are on opposite sides of the engine so just changing one of the existing to house rather then a starter is not an option. I am going to need to build new battery boxes to change up my configuration. That whole area is tight though so It is going be like a game of Tetris trying to get more batteries on the house side.

I have seen a few people recommend all the charging sources be placed on the house bank size. I assume this includes the engine alternator. Although I like the idea of the alternator going straight to the larger house bank, I am worried this could end up killing my alternator if I have the "start" battery witch on, crank the engine, but have the "house" battery switch off. With the alternator going to the House side I wont start the engine (in normal use) without the battery switch on. Thought, If I have the charging bus connected to the ACR which connects to the "on" starter battery side will this provide me cover so as not to kill my alternator? Is this a reliable option to depend on the ACR to close the Circuit when I start the engine? Am I wrong or does the ACR SI disconnect the battery during cranking and is this disconnect long enough to kill the alternator? I think I see what the point is of having all the charging on the House bus but I am still a little concerned about killing the alternator so some more input is appreciated.

Yes I agree, Mainesail has a great website. I reference a lot. I used it for installing new opening portlights, rebedding my hardware, and others.

Another area I would like to draw attention to is the AC common ground and where it connects to my DC negative bus. Everything I have read says this is correct to have one point where the AC ground connects to the DC negative but it still seems odd. Does this not energize all of my AC ground with DC negative? For devices with a case ground does this mean that if I happen to brush a DC positive wire against the case I will complete the circuit? Im sure I simple dont understand something but even though I have read this is correct several places I still dont feel great about it.

Intotheworld, your DC set up is pretty much the same as mine, except that I don't have on and offs, I used the existing 1-2-both but will be changing to on-offs.
I connected the alternator to the house bar, and I have the ACR input as the house and the output the reserve. I never ever use the reserve, that is why I call it that. I have a Victron to monitorvoltage for both banks to keep an eye on the state of charge.
BTW, what app did you use to draw the diagram and where did you get the icons? Neat!

Intotheworld, your DC set up is pretty much the same as mine, except that I don't have on and offs, I used the existing 1-2-both but will be changing to on-offs.

I connected the alternator to the house bar, and I have the ACR input as the house and the output the reserve. I never ever use the reserve, that is why I call it that. I have a Victron to monitor voltage for both banks to keep an eye on the state of charge.

BTW, what app did you use to draw the diagram and where did you get the icons? Neat!

Thanks. I used Microsoft Visio. I copied and pasted the images from google into my diagram. I am not familiar with technical wiring diagrams so having pictures of the product I'm actually using makes more sense to me. It should also make it easier in the future when I'm looking back at this and the pictures look like what is actually on the boat.

Do you start your engine with the house or reserve battery? I'm worried about what happens if I start the engine but have the house switch turned off.